Learned and learnt, burned and burnt; can someone please explain the difference/correct usage?

[tearinghairout]

Many thanks

One's American, one's English. I didn't know there were two options until I started a course in the US, and am constantly being corrected. UK is learnt, US is learned - at least that's what I've worked out.

Oh golly, don't say I've been using Americanisms all this time without knowing it...

I thought it was maybe to do with doing something to something, and having it done (come back! I can explain) e.g. I burned the cakes, the cakes were burnt. But I have no reason for thinking this.

They are 2 different tenses of the same verb - perfect and past i.e.

I have burned the cakes. (Past participle, perfect tense of the verb to burn)
I burnt the cakes (past tense of the verb to burn)

As a rule of thumb the latter is often used with the adjective as per your example - the cakes were burnt.

If we were French we would still use the 2 tenses.
If we were American we would only use the perfect tense, often dropping the 'have' in front to get 'I burned..' - for some unknown reason they tended towards this in the late 1800s and have stuck with it.
As for us we can use it anyway we like (though it's better to be consistent or it looks a bit odd).

Class dismissed. Now run along to your home economics class to learn how to not keep burning the cakes.

Michael Swan explains it in 'Practical English Usage':

burn, dream, lean, learn, smell, spill and spoil are all regular verbs in American English (ie burned, dreamed, etc). In British English they can be regular (burned), but irregular past tenses and participles with -t are more common (burnt, dreamt, leant etc).

My copy of this book is now nearly 20 years old, and I would no longer say that the -t endings are 'more common'. The way we use English is inevitably becoming more American as we are exposed to it more and more.

But I agree with ToffeePenny - just be consistent and you won't go wrong.

Toffeepenny & MotherMountainGoat - I've just revisited this and found your two replies. Many (belated) thanks. I shall go away and ponder!